April 20, 2015

Exciting news on the R2 front. JAG 01 is cut! JAG01 is the part number for the topmost ring in R2’s aluminum body. It’s by far the most complex part of the main body (along with the leg support panels).

Each of those holes (accurate to within +/-.005) mean that the FlowJet has to cycle on/off each time. In my experience teaching the tool, there is most likely to be a problem during a start/stop cycle. Yikes!

I’ve been putting off JAG01 for a few months now since it’s such a tough part and I didn’t want anything to go wrong. I laser cut the file in thin plywood using my Inventor .dxf file and it seemed right, but there’s nothing like actually water jetting a part to show you your errors. The FlowJet has been down for a few weeks at TechShop and they finally got it working again. I happened to be there when they did and the employee said they needed a test file. Would I like to run JAG01 in some scrap (too-thin) aluminum? YOU BET!

So we took about 12 minutes to run the file in some 18ga aluminum and I took the part and laid it out against my plywood version. Perfect fit! So I know the file worked fine. Now all I had to do was clamp the 1/4″ slab of 6061-T6 aluminum onto the table, take a deep breath, and go for it. I did that tonight and kept an eagle eye on the tool as it cut (not that I could salvage the part if anything went wrong). Fortunately, it worked! 18 minutes later I had a beautiful part resting on the FlowJet water surface and I could breathe again.

Below is a picture of all the pieces I have milled up in the past 6 months when I started this crazy project. Each part is accurate to within a few thousands of an inch. JAG01 is in the upper right.

And here’s the frame so far balanced precariously together.

Year 1 is the frame and I’m more or less on track to have it done in 4-5 months. I have to do two copies of JAG04 (the shoulder mounting plate), and then two copies of JAG20 (the shoulder flange). For JAG04 I’ll use the WaterJet again in combination with the manual mill. Then I need to go back in to a bunch of the holes that were WaterJet and either tap them with threads, or countersink a chamfer on the edge so the screws sit flush. For JAG20 I’ll be learning a whole new tool: the Tormek CNC Mill. That’ll take a month or two. I could buy the part online for about what it’s going to cost me to make it, but this project is about testing my boundaries and learning to do new things. I will have to buy some parts for R2 (the skin and dome), but I’m trying to do as much as I possibly can myself, and use the most difficult material (aluminum as opposed to wood). If I hose JAG20 I’ll consider buying the part, but I want to try first.

Once all the parts are done, drilled, tapped, countersunk, and fit together correctly, I’ll sandblast everything to remove milling scratches, then sandblast again using baking soda. Then it’s off to the anodizing step to give the frame a beautiful coat of anodized metal. Then I’ll laser etch a pattern into the frame.